1. Field of the Invention
The present invention relates to a lead frame retaining apparatus for retaining lead frames during the manufacture of semiconductor devices.
2. Prior Art
The apparatus disclosed in the Japanese Patent Application Publication (Kokoku) No. 4-74861 is one of the conventional lead frame retaining apparatuses.
In this apparatus, a frame retainer, that presses a lead frame against a heating block, is mounted in a detachable manner to a frame retainer holder by vacuum suction. When the frame retainer is held by the frame retainer holder by vacuum suction, the upper surface of the frame retainer is held (by means of vacuum suction) by the undersurface of the frame retainer holder. Positioning of the frame retainer in the length-wise direction is done using the inner side surfaces that are formed inside the undersurface of the frame retainer holder.
Thus, in this prior art, the upper surface of the frame retainer is held by the undersurface of the frame retainer holder by vacuum suction. Accordingly, if the vacuum is cut off as a result of, for example, vacuum system failure, the frame retainer will fall. In addition, since the frame retainer is held by the frame retainer holder via vacuum suction, the frame retainer is kept held for a short period of time after the vacuum has been cut. In this case, if the operator, believing that the vacuum is still on, operates the apparatus, the frame retainer falls.
Furthermore, the positioning of the frame retainer in the length-wise direction is accomplished using the inside side surfaces of the frame retainer holder. Thus, there are some more problems particularly when the frame retainer is replaced upon the change of the type of product being handled. In other words, the frame retainer suffers thermal expansion as a result of heat applied by the heating block; and if the thermal expansion occurs in the frame retainer, the frame retainer is tightly wedged in the frame retainer. If this happens, the frame retainer must be thoroughly cooled off before it is removed.